Rapid Detection of Chemical Contaminants

Synergising Food Safety, Quality and Regulatory Dimension for Excellence in Food Ecosystem

Dr. Anoop A. KrishnanAssistant Director

Export Inspection Council

New Frontiers in Food analysis

Introduction

DILUTE AND SHOOT

Introduction

❖ The contamination of food by chemical hazards is a worldwide public

health concern and is a leading cause of trade problems internationally.

❖ Chemical contaminants may occur in our food from various sources. They

typically pose a health concern, resulting in strict regulations of their

levels by national governments and internationally by the Codex

Alimentarius Commission.

❖ Analysis of relevant chemical contaminants is an essential part of food

safety testing programs to ensure consumer safety and compliance with

regulatory limits.

❖ Modern analytical techniques can determine known chemical

contaminants in complex food matrices at very low concentration levels.

Moreover, they can also help discover and identify new or unexpected

chemical contaminants.

Introduction

• In recent years, hyphenated techniques have received ever-

increasing attention as the principal means to solve complex

analytical problems. The power of combining separation

technologies with spectroscopic techniques has been demonstrated

over the years for both quantitative and qualitative analysis of

unknown compounds in complex natural product extracts or

fractions.

• To obtain structural information leading to the identification of the

compounds/speciation forms present in a crude sample resulted in

the introduction of various modern hyphenated techniques, e.g.,

CE-MS, GC-MS, LC-MS, LC-ICPMS and LC-NMR.

Chemical contaminant-Sources

Chemical contaminants can be present in foods mainly as a result of

the use of

✓ Agrochemicals, such as residues of pesticides and veterinary drugs

✓ Environmental Contaminants- Heavy metal, Dioxins etc.

✓ Food processing Contaminants- Nitrosamines, PAH etc.

✓ Migration from food packaging materials- Phthalates etc.

✓ Toxins- Mycotoxins, marine bio toxins etc.

✓ Unapproved food additives and adulterants- melamine, Sudan

dyes etc.

Cob web of Food safety

Evolution of analytical methodology

Ref: Modified from Seiber, J. N.,Regulation of Agrochemicals, American Chemical Society, Washington, D.C., 1991.

Technical innovation in Instrumentation

• The evolution of the analytical instrumentation used byvarious laboratories in the last seven years has drasticallychanged and new technical innovation and evolution havecome. The use of conventional detectors has decreased, givingway to triple quadrupoles, which are, without question, themost widely used instruments for both gas and liquidchromatography. In GC, single quadrupoles and ion trapshave been replaced by triple quadrupoles(LCMSMS/GCQQQ)

• During the last years the introduction of liquidchromatography high resolution mass spectrometry (LC-HRMS) has become popular in pesticide residueslaboratories. The advantages in getting exact mass of theanalytes have been evaluated giving an important and newsolution to common problems of these analyses.. Recentlynew GC-HRMS are intending to cover a similar position fortypical GC pesticide residues.

Whatever is there, find it!

Sample Preparation(extraction, cleanup,

concentration, digestion)

Instrumental Analysis

Data Processing

Sample Processing/Homogenization The techniques employed here

decide if the overall method is• Multi-Residue, • Single-Residue •Group-Specific

Interdependence of Analytical steps

Sample preparation is critical, any losses here... cannot be recovered afterwards!

All instrumental analysis techniques available have some inherent limitations in terms of …

Sensitivity,

Selectivity,

Robustness (matrix tolerance)

“Thus, sample preparation and instrumental analysis

always have to be observed together”

Sampling

Analysis of food contaminants

➢ One of the current trends in analyticalchemistry is the method development formany optimized tools used in classicalmethods.

➢ The basic analytical approach involves anextraction using a suitable solvent/digestionusing acids, clean up to remove interferingmatrix components, a chromatographicseparation and a selective detection.

➢ It is not an exaggeration to say that theimplementation of mass spectrometry (MS)as a detection technique has trulyrevolutionized the analysis of chemicalcontaminants in foods.

Analysis of food contaminants➢ As opposed to element-selective or non selective

detectors, MS can detect a wide range ofcompounds independent of their elementalcomposition and provide simultaneousquantitation and structural identification ofdetected analytes.

➢ Fast analysis, consumption of small amounts ofsamples and reagents, high sensitivity andautomation are some of the most important goalsdesired to be achieved.

➢ More generic Multiresidue, Multiclass analysismethodologies with high sensitivity and expandedscopes, which include as many compounds andcommodities as possible in a single method arebeing developed

Analytical Approach

➢ Whether a method is single or multiresidue in scope, it will includea series of discrete steps or unit processes whose ultimate goal is todetect and quantify specific chemicals at levels of interest, in arelatively complex food matrix.

➢ The matrix may contain hundreds or even thousands of natural andman-made chemicals which can potentially interfere with theanalyte(s) of interest, often at concentrations many-fold higher thanthose of the analytes. It is a proverbial “needle in the haystack”undertaking.

➢ Thus, methods must be designed to take advantage of uniquephysical properties, such as polarity, volatility, and opticalproperties, and chemical properties (reactivity, complex formation,combustion characteristics) which allow the analyte to stand outfrom the forest of matrix-derived interferences.

Analytical Approach

• Extraction: Remove the analyte from the matrix, leaving the bulk ofthe matrix behind as a filterable or non volatile mass.

• Clean up: Remove unwanted coextractives by such operations ascolumn chromatography, liquid-liquid partitioning, volatilization,or chemical degradation.

• Modification: Convert the target analyte to a derivative which ismore readily separated, detected, or quantitatively determined thanthe parent. Modification may be done pre- or post-cleanup, or afterthe resolution step in operations such as post-column derivitization.

• Resolution: Separate the analyte from remaining interferences,usually by some form of refined chromatography

Analytical Approach

• Detection — Obtain a response related to the amount of analytepresent. Chromatographic detectors, spectrophotometers, and massspectrometers are the mainstays for achieving this objective,although immunosorbent-based methods are coming into morecommon use.

• Measurement — Relate the response of the analyte to some knownstandard, of the analyte itself or a surrogate with similar properties,for calculating the concentration in the original matrix.

• Confirmation — Provide assurance that the primary method givescorrect (i.e., accurate and precise) results, by use of a second,independent method. This has become much more important inrecent years due to the emphasis on quality assurance/qualitycontrol (QA/QC) in the analytical laboratory.

Testing kits: immunoassay

From http://www.horiba.com

• Preliminary screening for particular known compounds• Advantage: low cost, speed and ease of use• Limitation: individual or small group of compounds only

High Selectivity in Instrumental Analysis gives more flexibility in sample preparation

GC/LC analysis

QuPPe, MiniLuke

QuEChERS, Ethylacetate (SWET)

Microwave digestion

MIPs/ImmunoaffinityColumn chromatographySolid Phase Extraction

Dispersive SPESelective extraction solventGeneric extraction solvent

GC-FIDGC-ECDGC-NPD/AASGC-FPD/Ultra HPLC/ICP-OES

GC-MS (quad/TOF)/LCMSMS/LC-TOFGCxGC-MS, GC-MS/MS, GC-hrMS, LC-hrMSGCxGC-hrMS, GC-QTOF, IRMS, APGC, TrapsOrbitrap/MS, MALDI-TOFMS, HPLC-ICPMS

Sample preparation

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In

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Power to discriminate:

Isomers

Metabolites

Megradation products

Matrix components

Endogenous compounds

New Frontiers in Food Analysis

Recoveries • Safe • Speed/Time • Clean-up efficiency • Cost

SPE

dSPE

Effective clean up

Easy of Use/Efficiancy (time)

New Frontiers in Food Analysis

New Frontiers in inorganic analysis

ICP-OES

ASV

AAS- Flame

Fast SequentialAAS

LC/IC-ICPMSICP-MS

AAS-FurnaceHydride

Detection limitsHigh (mg/kg) Low (µg/kg)

High

Number of elements

Low

Analytical requirements

Analytical Interlink

Check that Method Works

Check that Method is

reliable

Check that Laboratory can

use it

Performance measurement

Validation Proficiency Testing

Combination should be fit-for-purpose

Challenges

✓ Need for fast, reliable, harmonisedmultimethods for analysis of a range ofcontaminants and unknowns

✓ Food fraud = Global issue

Conclusion

➢ It has to be assured that the analytical methods used by official foodcontrol laboratories produce reliable results.

➢ Clearly, there has been a tradeoff in terms of investment and cost,such that a modern analytical laboratory must have an array ofhighly sophisticated and expensive instruments, and of equallysophisticated trained personnel to maintain, run, and interpret theresults of the instruments.

➢ The need for more and better analytical data will continue tostimulate developments in analytical chemistry applied to foods.

➢ Safer food, through rapid and cost-efficient tests for detectingchemical contaminants in food is the need of the hour.

From: Fear

To: Confidence

Conclusion

Thank you for your kind attention